update: fix bare update to work on new branch

So far bare update on new branch results in
'abort: branch new-branch not found'. This commit fixes
this by updating to the parent of wctx.

The effect of updating to the parent of wctx is to move to the paren't
branch - this means that it is no longer necessary to prevent you from
updating if you would lose your newly created branch.

mercurial/destutil.py

@@ -1,422 +1,418 b''
 # destutil.py - Mercurial utility function for command destination
 #
 #  Copyright Matt Mackall <[e-mail]> and other
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 from .i18n import _
 from . import (
     bookmarks,
     error,
     obsolete,
 )
 
 def _destupdatevalidate(repo, rev, clean, check):
     """validate that the destination comply to various rules
 
     This exists as its own function to help wrapping from extensions."""
     wc = repo[None]
     p1 = wc.p1()
     if not clean:
         # Check that the update is linear.
         #
         # Mercurial do not allow update-merge for non linear pattern
         # (that would be technically possible but was considered too confusing
         # for user a long time ago)
         #
         # See mercurial.merge.update for details
         if p1.rev() not in repo.changelog.ancestors([rev], inclusive=True):
             dirty = wc.dirty(missing=True)
             foreground = obsolete.foreground(repo, [p1.node()])
             if not repo[rev].node() in foreground:
                 if dirty:
                     msg = _("uncommitted changes")
                     hint = _("commit and merge, or update --clean to"
                              " discard changes")
                     raise error.UpdateAbort(msg, hint=hint)
                 elif not check:  # destination is not a descendant.
                     msg = _("not a linear update")
                     hint = _("merge or update --check to force update")
                     raise error.UpdateAbort(msg, hint=hint)
 
 def _destupdateobs(repo, clean, check):
     """decide of an update destination from obsolescence markers"""
     node = None
     wc = repo[None]
     p1 = wc.p1()
     movemark = None
 
     if p1.obsolete() and not p1.children():
         # allow updating to successors
         successors = obsolete.successorssets(repo, p1.node())
 
         # behavior of certain cases is as follows,
         #
         # divergent changesets: update to highest rev, similar to what
         #     is currently done when there are more than one head
         #     (i.e. 'tip')
         #
         # replaced changesets: same as divergent except we know there
         # is no conflict
         #
         # pruned changeset: no update is done; though, we could
         #     consider updating to the first non-obsolete parent,
         #     similar to what is current done for 'hg prune'
 
         if successors:
             # flatten the list here handles both divergent (len > 1)
             # and the usual case (len = 1)
             successors = [n for sub in successors for n in sub]
 
             # get the max revision for the given successors set,
             # i.e. the 'tip' of a set
             node = repo.revs('max(%ln)', successors).first()
             if bookmarks.isactivewdirparent(repo):
                 movemark = repo['.'].node()
     return node, movemark, None
 
 def _destupdatebook(repo, clean, check):
     """decide on an update destination from active bookmark"""
     # we also move the active bookmark, if any
     activemark = None
     node, movemark = bookmarks.calculateupdate(repo.ui, repo, None)
     if node is not None:
         activemark = node
     return node, movemark, activemark
 
 def _destupdatebranch(repo, clean, check):
     """decide on an update destination from current branch
 
     This ignores closed branch heads.
     """
     wc = repo[None]
     movemark = node = None
     currentbranch = wc.branch()
     if currentbranch in repo.branchmap():
         heads = repo.branchheads(currentbranch)
         if heads:
             node = repo.revs('max(.::(%ln))', heads).first()
         if bookmarks.isactivewdirparent(repo):
             movemark = repo['.'].node()
     else:
-        if currentbranch == 'default': # no default branch!
-            # update to the tipmost non-closed branch head
-            node = repo.revs('max(head() and not closed())').first()
-        else:
-            raise error.Abort(_("branch %s not found") % currentbranch)
+        node = repo['.'].node()
     return node, movemark, None
 
 def _destupdatebranchfallback(repo, clean, check):
     """decide on an update destination from closed heads in current branch"""
     wc = repo[None]
     currentbranch = wc.branch()
     movemark = None
     if currentbranch in repo.branchmap():
         # here, all descendant branch heads are closed
         heads = repo.branchheads(currentbranch, closed=True)
         assert heads, "any branch has at least one head"
         node = repo.revs('max(.::(%ln))', heads).first()
         assert node is not None, ("any revision has at least "
                                   "one descendant branch head")
         if bookmarks.isactivewdirparent(repo):
             movemark = repo['.'].node()
     else:
         # here, no "default" branch, and all branches are closed
         node = repo.lookup('tip')
         assert node is not None, "'tip' exists even in empty repository"
     return node, movemark, None
 
 # order in which each step should be evalutated
 # steps are run until one finds a destination
 destupdatesteps = ['evolution', 'bookmark', 'branch', 'branchfallback']
 # mapping to ease extension overriding steps.
 destupdatestepmap = {'evolution': _destupdateobs,
                      'bookmark': _destupdatebook,
                      'branch': _destupdatebranch,
                      'branchfallback': _destupdatebranchfallback,
                      }
 
 def destupdate(repo, clean=False, check=False):
     """destination for bare update operation
 
     return (rev, movemark, activemark)
 
     - rev: the revision to update to,
     - movemark: node to move the active bookmark from
                 (cf bookmark.calculate update),
     - activemark: a bookmark to activate at the end of the update.
     """
     node = movemark = activemark = None
 
     for step in destupdatesteps:
         node, movemark, activemark = destupdatestepmap[step](repo, clean, check)
         if node is not None:
             break
     rev = repo[node].rev()
 
     _destupdatevalidate(repo, rev, clean, check)
 
     return rev, movemark, activemark
 
 msgdestmerge = {
     # too many matching divergent bookmark
     'toomanybookmarks':
         {'merge':
             (_("multiple matching bookmarks to merge -"
                " please merge with an explicit rev or bookmark"),
              _("run 'hg heads' to see all heads")),
          'rebase':
             (_("multiple matching bookmarks to rebase -"
                " please rebase to an explicit rev or bookmark"),
              _("run 'hg heads' to see all heads")),
         },
     # no other matching divergent bookmark
     'nootherbookmarks':
         {'merge':
             (_("no matching bookmark to merge - "
                "please merge with an explicit rev or bookmark"),
              _("run 'hg heads' to see all heads")),
          'rebase':
             (_("no matching bookmark to rebase - "
                "please rebase to an explicit rev or bookmark"),
              _("run 'hg heads' to see all heads")),
         },
     # branch have too many unbookmarked heads, no obvious destination
     'toomanyheads':
         {'merge':
             (_("branch '%s' has %d heads - please merge with an explicit rev"),
              _("run 'hg heads .' to see heads")),
          'rebase':
             (_("branch '%s' has %d heads - please rebase to an explicit rev"),
              _("run 'hg heads .' to see heads")),
         },
     # branch have no other unbookmarked heads
     'bookmarkedheads':
         {'merge':
             (_("heads are bookmarked - please merge with an explicit rev"),
              _("run 'hg heads' to see all heads")),
          'rebase':
             (_("heads are bookmarked - please rebase to an explicit rev"),
              _("run 'hg heads' to see all heads")),
         },
     # branch have just a single heads, but there is other branches
     'nootherbranchheads':
         {'merge':
             (_("branch '%s' has one head - please merge with an explicit rev"),
              _("run 'hg heads' to see all heads")),
          'rebase':
             (_("branch '%s' has one head - please rebase to an explicit rev"),
              _("run 'hg heads' to see all heads")),
         },
     # repository have a single head
     'nootherheads':
         {'merge':
             (_('nothing to merge'),
             None),
          'rebase':
             (_('nothing to rebase'),
             None),
         },
     # repository have a single head and we are not on it
     'nootherheadsbehind':
         {'merge':
             (_('nothing to merge'),
              _("use 'hg update' instead")),
          'rebase':
             (_('nothing to rebase'),
              _("use 'hg update' instead")),
         },
     # We are not on a head
     'notatheads':
         {'merge':
             (_('working directory not at a head revision'),
              _("use 'hg update' or merge with an explicit revision")),
          'rebase':
             (_('working directory not at a head revision'),
              _("use 'hg update' or rebase to an explicit revision"))
         },
     'emptysourceset':
         {'merge':
             (_('source set is empty'),
              None),
          'rebase':
             (_('source set is empty'),
              None),
         },
     'multiplebranchessourceset':
         {'merge':
             (_('source set is rooted in multiple branches'),
              None),
          'rebase':
             (_('rebaseset is rooted in multiple named branches'),
              _('specify an explicit destination with --dest')),
         },
     }
 
 def _destmergebook(repo, action='merge', sourceset=None):
     """find merge destination in the active bookmark case"""
     node = None
     bmheads = repo.bookmarkheads(repo._activebookmark)
     curhead = repo[repo._activebookmark].node()
     if len(bmheads) == 2:
         if curhead == bmheads[0]:
             node = bmheads[1]
         else:
             node = bmheads[0]
     elif len(bmheads) > 2:
         msg, hint = msgdestmerge['toomanybookmarks'][action]
         raise error.ManyMergeDestAbort(msg, hint=hint)
     elif len(bmheads) <= 1:
         msg, hint = msgdestmerge['nootherbookmarks'][action]
         raise error.NoMergeDestAbort(msg, hint=hint)
     assert node is not None
     return node
 
 def _destmergebranch(repo, action='merge', sourceset=None, onheadcheck=True):
     """find merge destination based on branch heads"""
     node = None
 
     if sourceset is None:
         sourceset = [repo[repo.dirstate.p1()].rev()]
         branch = repo.dirstate.branch()
     elif not sourceset:
         msg, hint = msgdestmerge['emptysourceset'][action]
         raise error.NoMergeDestAbort(msg, hint=hint)
     else:
         branch = None
         for ctx in repo.set('roots(%ld::%ld)', sourceset, sourceset):
             if branch is not None and ctx.branch() != branch:
                 msg, hint = msgdestmerge['multiplebranchessourceset'][action]
                 raise error.ManyMergeDestAbort(msg, hint=hint)
             branch = ctx.branch()
 
     bheads = repo.branchheads(branch)
     onhead = repo.revs('%ld and %ln', sourceset, bheads)
     if onheadcheck and not onhead:
         # Case A: working copy if not on a head. (merge only)
         #
         # This is probably a user mistake We bailout pointing at 'hg update'
         if len(repo.heads()) <= 1:
             msg, hint = msgdestmerge['nootherheadsbehind'][action]
         else:
             msg, hint = msgdestmerge['notatheads'][action]
         raise error.Abort(msg, hint=hint)
     # remove heads descendants of source from the set
     bheads = list(repo.revs('%ln - (%ld::)', bheads, sourceset))
     # filters out bookmarked heads
     nbhs = list(repo.revs('%ld - bookmark()', bheads))
     if len(nbhs) > 1:
         # Case B: There is more than 1 other anonymous heads
         #
         # This means that there will be more than 1 candidate. This is
         # ambiguous. We abort asking the user to pick as explicit destination
         # instead.
         msg, hint = msgdestmerge['toomanyheads'][action]
         msg %= (branch, len(bheads) + 1)
         raise error.ManyMergeDestAbort(msg, hint=hint)
     elif not nbhs:
         # Case B: There is no other anonymous heads
         #
         # This means that there is no natural candidate to merge with.
         # We abort, with various messages for various cases.
         if bheads:
             msg, hint = msgdestmerge['bookmarkedheads'][action]
         elif len(repo.heads()) > 1:
             msg, hint = msgdestmerge['nootherbranchheads'][action]
             msg %= branch
         elif not onhead:
             # if 'onheadcheck == False' (rebase case),
             # this was not caught in Case A.
             msg, hint = msgdestmerge['nootherheadsbehind'][action]
         else:
             msg, hint = msgdestmerge['nootherheads'][action]
         raise error.NoMergeDestAbort(msg, hint=hint)
     else:
         node = nbhs[0]
     assert node is not None
     return node
 
 def destmerge(repo, action='merge', sourceset=None, onheadcheck=True):
     """return the default destination for a merge
 
     (or raise exception about why it can't pick one)
 
     :action: the action being performed, controls emitted error message
     """
     if repo._activebookmark:
         node = _destmergebook(repo, action=action, sourceset=sourceset)
     else:
         node = _destmergebranch(repo, action=action, sourceset=sourceset,
                                 onheadcheck=onheadcheck)
     return repo[node].rev()
 
 histeditdefaultrevset = 'reverse(only(.) and not public() and not ::merge())'
 
 def desthistedit(ui, repo):
     """Default base revision to edit for `hg histedit`."""
     # Avoid cycle: scmutil -> revset -> destutil
     from . import scmutil
 
     default = ui.config('histedit', 'defaultrev', histeditdefaultrevset)
     if default:
         revs = scmutil.revrange(repo, [default])
         if revs:
             # The revset supplied by the user may not be in ascending order nor
             # take the first revision. So do this manually.
             revs.sort()
             return revs.first()
 
     return None
 
 def _statusotherbook(ui, repo):
     bmheads = repo.bookmarkheads(repo._activebookmark)
     curhead = repo[repo._activebookmark].node()
     if repo.revs('%n and parents()', curhead):
         # we are on the active bookmark
         bmheads = [b for b in bmheads if curhead != b]
         if bmheads:
             msg = _('%i other divergent bookmarks for "%s"\n')
             ui.status(msg % (len(bmheads), repo._activebookmark))
 
 def _statusotherbranchheads(ui, repo):
     currentbranch = repo.dirstate.branch()
     allheads = repo.branchheads(currentbranch, closed=True)
     heads = repo.branchheads(currentbranch)
     if repo.revs('%ln and parents()', allheads):
         # we are on a head, even though it might be closed
         #
         #  on closed otherheads
         #  ========= ==========
         #      o        0       all heads for current branch are closed
         #               N       only descendant branch heads are closed
         #      x        0       there is only one non-closed branch head
         #               N       there are some non-closed branch heads
         #  ========= ==========
         otherheads = repo.revs('%ln - parents()', heads)
         if repo['.'].closesbranch():
             ui.warn(_('no open descendant heads on branch "%s", '
                         'updating to a closed head\n') %
                       (currentbranch))
             if otherheads:
                 ui.warn(_('(committing will reopen the head, '
                             'use `hg heads .` to see %i other heads)\n') %
                           (len(otherheads)))
             else:
                 ui.warn(_('(committing will reopen branch "%s")\n') %
                           (currentbranch))
         elif otherheads:
             ui.status(_('%i other heads for branch "%s"\n') %
                       (len(otherheads), currentbranch))
 
 def statusotherdests(ui, repo):
     """Print message about other head"""
     # XXX we should probably include a hint:
     # - about what to do
     # - how to see such heads
     if repo._activebookmark:
         _statusotherbook(ui, repo)
     else:
         _statusotherbranchheads(ui, repo)

tests/test-newbranch.t

@@ -1,347 +1,393 b''
   $ branchcache=.hg/cache/branch2
 
   $ listbranchcaches() {
   >    for f in .hg/cache/branch2*;
   >       do echo === $f ===;
   >       cat $f;
   >     done;
   > }
   $ purgebranchcaches() {
   >     rm .hg/cache/branch2*
   > }
 
   $ hg init t
   $ cd t
 
   $ hg branches
   $ echo foo > a
   $ hg add a
   $ hg ci -m "initial"
   $ hg branch foo
   marked working directory as branch foo
   (branches are permanent and global, did you want a bookmark?)
   $ hg branch
   foo
   $ hg ci -m "add branch name"
   $ hg branch bar
   marked working directory as branch bar
   $ hg ci -m "change branch name"
 
 Branch shadowing:
 
   $ hg branch default
   abort: a branch of the same name already exists
   (use 'hg update' to switch to it)
   [255]
 
   $ hg branch -f default
   marked working directory as branch default
 
   $ hg ci -m "clear branch name"
   created new head
 
 There should be only one default branch head
 
   $ hg heads .
   changeset:   3:1c28f494dae6
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     clear branch name
   
 Merging and branches
 
   $ hg co foo
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg branch
   foo
 
  set existing branch name fails unless force - setting existing parent branch works without force:
 
   $ hg branch bar
   abort: a branch of the same name already exists
   (use 'hg update' to switch to it)
   [255]
 
   $ hg branch -f bar
   marked working directory as branch bar
 
   $ hg branch foo
   marked working directory as branch foo
 
   $ echo bleah > a
   $ hg ci -m "modify a branch"
 
   $ hg merge default
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
 
   $ hg branch
   foo
 
  set existing branch name where branch head is ancestor:
 
   $ hg branch bar
   abort: a branch of the same name already exists
   (use 'hg update' to switch to it)
   [255]
 
  set (other) parent branch as branch name
 
   $ hg branch default
   marked working directory as branch default
 
  set (first) parent branch as branch name
 
   $ hg branch foo
   marked working directory as branch foo
 
   $ hg ci -m "merge"
 
   $ hg log -G -T '{rev}:{node|short} {branch} {desc}\n'
   @    5:530046499edf foo merge
   |\
   | o  4:adf1a74a7f7b foo modify a branch
   | |
   o |  3:1c28f494dae6 default clear branch name
   | |
   o |  2:c21617b13b22 bar change branch name
   |/
   o  1:6c0e42da283a foo add branch name
   |
   o  0:db01e8ea3388 default initial
   
   $ hg branches
   foo                            5:530046499edf
   default                        3:1c28f494dae6 (inactive)
   bar                            2:c21617b13b22 (inactive)
 
   $ hg branches -q
   foo
   default
   bar
 
 Test for invalid branch cache:
 
   $ hg rollback
   repository tip rolled back to revision 4 (undo commit)
   working directory now based on revisions 4 and 3
 
   $ cp ${branchcache}-served .hg/bc-invalid
 
   $ hg log -r foo
   changeset:   4:adf1a74a7f7b
   branch:      foo
   tag:         tip
   parent:      1:6c0e42da283a
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     modify a branch
   
   $ cp .hg/bc-invalid $branchcache
 
   $ hg --debug log -r foo
   changeset:   4:adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6
   branch:      foo
   tag:         tip
   phase:       draft
   parent:      1:6c0e42da283a56b5edc5b4fadb491365ec7f5fa8
   parent:      -1:0000000000000000000000000000000000000000
   manifest:    1:8c342a37dfba0b3d3ce073562a00d8a813c54ffe
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   files:       a
   extra:       branch=foo
   description:
   modify a branch
   
   
   $ purgebranchcaches
   $ echo corrupted > $branchcache
 
   $ hg log -qr foo
   4:adf1a74a7f7b
 
   $ listbranchcaches
   === .hg/cache/branch2 ===
   corrupted
   === .hg/cache/branch2-served ===
   adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6 4
   c21617b13b220988e7a2e26290fbe4325ffa7139 o bar
   1c28f494dae69a2f8fc815059d257eccf3fcfe75 o default
   adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6 o foo
 
 Push should update the branch cache:
 
   $ hg init ../target
 
 Pushing just rev 0:
 
   $ hg push -qr 0 ../target
 
   $ (cd ../target/; listbranchcaches)
   === .hg/cache/branch2-base ===
   db01e8ea3388fd3c7c94e1436ea2bd6a53d581c5 0
   db01e8ea3388fd3c7c94e1436ea2bd6a53d581c5 o default
 
 Pushing everything:
 
   $ hg push -qf ../target
 
   $ (cd ../target/; listbranchcaches)
   === .hg/cache/branch2-base ===
   adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6 4
   c21617b13b220988e7a2e26290fbe4325ffa7139 o bar
   1c28f494dae69a2f8fc815059d257eccf3fcfe75 o default
   adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6 o foo
 
 Update with no arguments: tipmost revision of the current branch:
 
   $ hg up -q -C 0
   $ hg up -q
   $ hg id
   1c28f494dae6
 
   $ hg up -q 1
   $ hg up -q
   $ hg id
   adf1a74a7f7b (foo) tip
 
   $ hg branch foobar
   marked working directory as branch foobar
 
   $ hg up
-  abort: branch foobar not found
-  [255]
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
 Fast-forward merge:
 
   $ hg branch ff
   marked working directory as branch ff
 
   $ echo ff > ff
   $ hg ci -Am'fast forward'
   adding ff
 
   $ hg up foo
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
 
   $ hg merge ff
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
 
   $ hg branch
   foo
   $ hg commit -m'Merge ff into foo'
   $ hg parents
   changeset:   6:185ffbfefa30
   branch:      foo
   tag:         tip
   parent:      4:adf1a74a7f7b
   parent:      5:1a3c27dc5e11
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     Merge ff into foo
   
   $ hg manifest
   a
   ff
 
 
 Test merging, add 3 default heads and one test head:
 
   $ cd ..
   $ hg init merges
   $ cd merges
   $ echo a > a
   $ hg ci -Ama
   adding a
 
   $ echo b > b
   $ hg ci -Amb
   adding b
 
   $ hg up 0
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ echo c > c
   $ hg ci -Amc
   adding c
   created new head
 
   $ hg up 0
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ echo d > d
   $ hg ci -Amd
   adding d
   created new head
 
   $ hg up 0
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg branch test
   marked working directory as branch test
   (branches are permanent and global, did you want a bookmark?)
   $ echo e >> e
   $ hg ci -Ame
   adding e
 
   $ hg log
   changeset:   4:3a1e01ed1df4
   branch:      test
   tag:         tip
   parent:      0:cb9a9f314b8b
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     e
   
   changeset:   3:980f7dc84c29
   parent:      0:cb9a9f314b8b
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     d
   
   changeset:   2:d36c0562f908
   parent:      0:cb9a9f314b8b
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     c
   
   changeset:   1:d2ae7f538514
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     b
   
   changeset:   0:cb9a9f314b8b
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     a
   
 Implicit merge with test branch as parent:
 
   $ hg merge
   abort: branch 'test' has one head - please merge with an explicit rev
   (run 'hg heads' to see all heads)
   [255]
   $ hg up -C default
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
 
 Implicit merge with default branch as parent:
 
   $ hg merge
   abort: branch 'default' has 3 heads - please merge with an explicit rev
   (run 'hg heads .' to see heads)
   [255]
 
 3 branch heads, explicit merge required:
 
   $ hg merge 2
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg ci -m merge
 
 2 branch heads, implicit merge works:
 
   $ hg merge
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
 
   $ cd ..
+
+We expect that bare update on new branch, updates to parent
+
+  $ hg init bareupdateonnewbranch
+  $ cd bareupdateonnewbranch
+  $ hg update
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ touch a
+  $ hg commit -A -m "a"
+  adding a
+  $ touch b
+  $ hg commit -A -m "b"
+  adding b
+  $ touch c
+  $ hg commit -A -m "c"
+  adding c
+  $ hg update -r 1
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg log -G
+  o  changeset:   2:991a3460af53
+  |  tag:         tip
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     c
+  |
+  @  changeset:   1:0e067c57feba
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     b
+  |
+  o  changeset:   0:3903775176ed
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     a
+  
+  $ hg branch dev
+  marked working directory as branch dev
+  (branches are permanent and global, did you want a bookmark?)
+  $ hg update
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg summary
+  parent: 1:0e067c57feba 
+   b
+  branch: dev
+  commit: (new branch)
+  update: (current)
+  phases: 3 draft